1. Field of the Invention
This invention relates to a motor, and more particularly to a motor, in which a bearing of a motor shaft and a brush holder adjoin each other.
2. Description of the Prior Art
In general, in a motor, an armature shaft is rotatably supported on a motor housing using a ball and roller bearing. A commutator and an armature are fixedly mounted on the outer periphery of the armature shaft, adjoining the ball and roller bearing. And further, brushes are arranged to be in sliding contact with the commutator. When electric power is supplied to the armature through the brushes and the commutator, the magnetic lines of force of the armature cross the magnetic fields of field magnets, so that the armature shaft can be rotatably driven.
However, in the motor of the type described, nothing is provided for preventing the abrasion dust of the carbon brushes from scattering in a space portion extending between the bearing and the brushes, whereby such disadvantages are presented that the abrasion dust of the carbon brushes intrudes into the ball and roller bearing to reduce the life of the bearing, or grease sealed in the ball and roller bearing scatters and adheres to a commutating portion, whereby the commutating function is lowered, thus resulting in a shortened life of the motor.
To counter this situation, in some cases, a sealed type ball and roller bearing is used, however, the effect of preventing the intrusion is not satisfactory. Furthermore, in order to prevent the grease of the ball and roller bearing from adhering to the commutating portion, it is known that an oil stopper is fixed to the armature shaft, with which, however, the abrasion dust of the carbon brushes cannot be prevented from intruding into the bearing.